现在进行时的构成是 be + 动词ing。以下是一些现在进行时的例句：

1. I am watching TV.

2. She is doing her homework.

3. They are having lunch.

4. I am reading a book now.

5. He is singing a song.

6. We are playing basketball.

7. What are they doing？

8. What is he doing？

这些例句展示了现在进行时在不同句子中的用法，希望对你有所帮助。